Express this product in scientific notation: $(2.10\times 10^{-3})\times (8.00\times 10^{4})$
Start by collecting like terms together. $= (2.10\times 8.00) \times (10^{-3}\times 10^{4})$ When multiplying exponents with the same base, add the powers together. $= 16.8 \times 10^{-3\,+\,4}$ $= 16.8 \times 10^{1}$ To write the answer correctly in scientific notation, the first number needs to be between $1$ and $10$ . In this case, we need to move the decimal one position to the left without changing the value of our answer. $ $ We can use the fact that $16.8$ is the same as $1.680 \times 10$ $ = {1.680 \times 10} \times 10^{1} $ $= 1.680\times 10^{2}$